fn main() {
    string s = 'hello world'

    var l = s as [u8]
    l[0] = 110
    (l[1], l[2]) = (l[2], l[1])
    println(s)
    println(l as string)

    [u8] l2 = [110, 105, 99, 101]

    string s2 = s + ' one piece'

    println(s2)

    string s3 = s2 + ' ' + l2 as string
    println(s3)


    // 字符串比较操作
    var b = 'hello world' == 'hello world'
    println(b) // true
    println('hello world' != 'hello world') // false
    println('a' < 'b') // true
    println('a' > 'b') // false
}